And I'm Robert Siegel. The fighting goes on in Iraq between government forces and Sunni groups led by extremist militants. At the same time, there are reports of escalating sectarian violence. The militant group ISIS has taken swaths of Northern and Western Iraq in a matter of days and continues to push into new territory. In a moment, we'll hear more about the broad ambitions ISIS has to conquer the region. But first, NPR's Leila Fadel joins us from Erbil with the latest on today's violence. Leila, what's happened today?

LEILA FADEL, BYLINE: Huge battles continue between the Islamic State of Iraq and Syria and the Shiite dominated government security forces, as well as the Kurdish Peshmerga in the North, as they try to advance towards Baghdad and towards the Syrian border. Civilians were reported killed in shelling attacks. Police claim they found 18 bodies of security forces outside Baghdad. And this follows on a huge battle in the city of the Baqubah, which is just northeast of Baghdad, in which ISIS attacked a police station and police fended them off. Forty-four prisoners died in that process. The police say that ISIS killed them when they launched mortars there. But others accuse the police of shooting the detainees, which are presumed to be Sunni men.

SIEGEL: Is this a sign, Leila, of sectarian reprisal killings on the part of the Shiite dominated security forces? Maybe the militias fighting with them?

FADEL: Well, it's really unclear what happened there, but if true, it is reminiscent of 2006 and 2007, when Shiite militias and Shiite-dominated security forces were accused of rounding up Sunni men and killing them in sectarian violence that was ripping the nation apart. That continued to a certain extent but had tapered off. And now, if true and it's coming back, we're seeing the signs of a new sectarian war here in Iraq.

SIEGEL: Well, as you've said, sectarian violence is nothing new in Iraq. Is the country really at risk of breaking apart this time?

FADEL: Well, analysts and experts say that this is the closest that Iraq has ever been to breaking into pieces along sectarian and ethnic lines. The Kurds in the North are using this opportunity to solidify what they see as their borders of a future independent state. The Shiites are rallying in Baghdad and further south to defend themselves from an onslaught of Sunni militants. And in the center, you're seeing ISIS take control of huge parts of the territory. The UN envoy to Baghdad told the French wire service AFP that this is the biggest threat to Iraq's sovereignty and territorial integrity that it's seen in years.

SIEGEL: And there have been calls for Prime Minister Nouri al-Maliki to go, haven't there?

FADEL: He is a seriously divisive figure. He's seen among the Sunni Arab community as corrupt and sectarian. He's also seen as somebody who purposely put his cronies in top positions in the security forces to keep himself in power, the same security force that crumbled in the face of an ISIS advance. And now he's fired four of his top security officials in order to save face, apparently. But maybe it's too late. It's unclear if this man can really survive a crisis like this, when everybody's looking to him as the man who's opened a space for a militant group like this to come into Iraq.

SIEGEL: Are there any obvious alternatives to him? People, when they say Maliki should go, do they have proposals of who should replace him?

FADEL: People want a more inclusive government. They want a government that represents more fully the different ethnicities and sects that exist in Iraq. Right now, when people look to Baghdad, they see a Shiite dominated government. They want a more national - a government that's more national unity and protects all Iraqis, not just one part of Iraq.